Background In perinatal dairy cows,ketosis is a prevalent metabolic disorder that lowers milk output and per-formance.Mitochondrial dysfunction and chronic inflammation in mammary tissue are linked to elevated blood k...Background In perinatal dairy cows,ketosis is a prevalent metabolic disorder that lowers milk output and per-formance.Mitochondrial dysfunction and chronic inflammation in mammary tissue are linked to elevated blood ketone levels,particularlyβ-hydroxybutyrate(BHB).Recent research has linked cytosolic mitochondrial DNA(mtDNA)with chronic aseptic inflammation by activating the cGAS-STING pathway during metabolic disorders,while autophagy activation effectively reverses this process.However,whether it is involved in mammary gland damage during ketosis is poorly understood.Therefore,this study aimed to explore the underlying mechanisms of mtDNA-induced inflammation under BHB stress and evaluate the potential therapeutic strategy of autophagy activation in mitigating this damage.Results Our study found an increased cytoplasmic mtDNA abundance in mammary gland tissues of dairy cows with ketosis and bovine mammary epithelial cell line(MAC-T)subjected to BHB stress.Further investigations revealed the activation of the cGAS-STING pathway and inflammatory response,indicated by elevated levels of cGAS and STING,along with increased phosphorylation levels of TBK1,P65,and IκB,and higher transcript levels of pro-inflammatory factors(IL-1B,IL-6,and TNF-α)in both in vivo and in vitro experiments.Notably,STING inhibition via si-STING transfection reversed BHB-induced inflammation.Additionally,autophagy activation appeared to protect against BHB stress by facilitating the removal of cytoplasmic mtDNA and preventing cGAS-STING pathway-mediated inflammation.Conclusions The findings illustrate that elevated BHB levels lead to the release of cytoplasmic mtDNA,which in turn activates the cGAS-STING pathway and triggers an inflammatory response in the mammary glands during hyper-ketonemia.Conversely,autophagy activation has been shown to alleviate this process by promoting cytoplasmic mtDNA degradation.展开更多
Background Subacute ruminal acidosis(SARA)causes an increase in endotoxin,which can induce immune and inflammatory responses in the ruminal epithelium of dair y cows.In non-ruminants,epigallocatechin-3-gallate(EGCG),a...Background Subacute ruminal acidosis(SARA)causes an increase in endotoxin,which can induce immune and inflammatory responses in the ruminal epithelium of dair y cows.In non-ruminants,epigallocatechin-3-gallate(EGCG),a major bioactive ingredient of green tea,is well-known to alleviate inflammation.Whether EGCG confers protection against SARA-induced inflammation and the underlying mechanisms are unknown.Results In vivo,eight ruminally cannulated Holstein cows in mid-lactation were randomly assigned to either a low-concentrate(40%)diet(CON)or a high-concentrate(60%)diet(HC)for 3 weeks to induce SARA(n=4).Cows with SARA had greater serum coccentrations of tumor necrosis factor(TNF)-αand interleukin-6,and epitheliu m had histological signs of damage.In vitro,immortalized bovine ruminal epithelial cells(BREC)were treated with lipopolysaccharide(LPS)to imitate the inflammatory damage caused by SARA.Our data revealed that BREC treated with 10 pg/mL LPS for 6 h successfully induce a robust inflammatory response as indicated by increased phosphorylation of IKBa and nuclear factor kappa-B(NF-κB)p65.Pre-treatment of BREC with 50μmol/L EGCG for 6 h before LPS challenge promoted the degradation of NLR family pyrin domain containing 3(NLRP3)inflammasome through activation of autophagy,which further repressed activation of NF-κB pathway targeting Toll-like receptor4(TLR4).Analyses also revealed that the ECGG upregulated tight junction(TJ)protein expression upon incubation with LPS.Conclusions Subacute ruminal acidosis causes ruminal epithelium injury and systemic inflammation in dairy cows.However,the anti-in flammatory effects of EGCG help preserve the integrity of the epithelial barrier through activating autophagy when BREC are exposed to LPS.Thus,EGCG could potentially serve as an e,fifective therapeutic agent for SARA-associated inflammation.展开更多
基金supported by the National Natural Science Foundation of China(32125038)the National Key R&B Program of China(2023YFD1801100)China Agriculture Research System(CARS-36).
文摘Background In perinatal dairy cows,ketosis is a prevalent metabolic disorder that lowers milk output and per-formance.Mitochondrial dysfunction and chronic inflammation in mammary tissue are linked to elevated blood ketone levels,particularlyβ-hydroxybutyrate(BHB).Recent research has linked cytosolic mitochondrial DNA(mtDNA)with chronic aseptic inflammation by activating the cGAS-STING pathway during metabolic disorders,while autophagy activation effectively reverses this process.However,whether it is involved in mammary gland damage during ketosis is poorly understood.Therefore,this study aimed to explore the underlying mechanisms of mtDNA-induced inflammation under BHB stress and evaluate the potential therapeutic strategy of autophagy activation in mitigating this damage.Results Our study found an increased cytoplasmic mtDNA abundance in mammary gland tissues of dairy cows with ketosis and bovine mammary epithelial cell line(MAC-T)subjected to BHB stress.Further investigations revealed the activation of the cGAS-STING pathway and inflammatory response,indicated by elevated levels of cGAS and STING,along with increased phosphorylation levels of TBK1,P65,and IκB,and higher transcript levels of pro-inflammatory factors(IL-1B,IL-6,and TNF-α)in both in vivo and in vitro experiments.Notably,STING inhibition via si-STING transfection reversed BHB-induced inflammation.Additionally,autophagy activation appeared to protect against BHB stress by facilitating the removal of cytoplasmic mtDNA and preventing cGAS-STING pathway-mediated inflammation.Conclusions The findings illustrate that elevated BHB levels lead to the release of cytoplasmic mtDNA,which in turn activates the cGAS-STING pathway and triggers an inflammatory response in the mammary glands during hyper-ketonemia.Conversely,autophagy activation has been shown to alleviate this process by promoting cytoplasmic mtDNA degradation.
基金supported by the National Natural Science Foundation of China(Beijing,China,grant nos.32125038)。
文摘Background Subacute ruminal acidosis(SARA)causes an increase in endotoxin,which can induce immune and inflammatory responses in the ruminal epithelium of dair y cows.In non-ruminants,epigallocatechin-3-gallate(EGCG),a major bioactive ingredient of green tea,is well-known to alleviate inflammation.Whether EGCG confers protection against SARA-induced inflammation and the underlying mechanisms are unknown.Results In vivo,eight ruminally cannulated Holstein cows in mid-lactation were randomly assigned to either a low-concentrate(40%)diet(CON)or a high-concentrate(60%)diet(HC)for 3 weeks to induce SARA(n=4).Cows with SARA had greater serum coccentrations of tumor necrosis factor(TNF)-αand interleukin-6,and epitheliu m had histological signs of damage.In vitro,immortalized bovine ruminal epithelial cells(BREC)were treated with lipopolysaccharide(LPS)to imitate the inflammatory damage caused by SARA.Our data revealed that BREC treated with 10 pg/mL LPS for 6 h successfully induce a robust inflammatory response as indicated by increased phosphorylation of IKBa and nuclear factor kappa-B(NF-κB)p65.Pre-treatment of BREC with 50μmol/L EGCG for 6 h before LPS challenge promoted the degradation of NLR family pyrin domain containing 3(NLRP3)inflammasome through activation of autophagy,which further repressed activation of NF-κB pathway targeting Toll-like receptor4(TLR4).Analyses also revealed that the ECGG upregulated tight junction(TJ)protein expression upon incubation with LPS.Conclusions Subacute ruminal acidosis causes ruminal epithelium injury and systemic inflammation in dairy cows.However,the anti-in flammatory effects of EGCG help preserve the integrity of the epithelial barrier through activating autophagy when BREC are exposed to LPS.Thus,EGCG could potentially serve as an e,fifective therapeutic agent for SARA-associated inflammation.
